Caffeine has a half life of roughly 2.5 to 4 hours. Which means that in that amount of time half of the caffeine will have been metabolized by your body. Caffeine only last a few hours depending on the consumption and your activity.
The amount of time spent playing video games has a negative correlation with academic performance (Gentile, D. 2004).On the other hand children also learn obsessive language and violent behavior from these violent video games which disturb child's mental status.
At the same time, despite claiming the review demonstrates a link between playing violent video games and aggression, the authors acknowledged that some studies were inconsistent and that present research is insufficient to establish whether this can lead to criminal violence or delinquency.